Much of the popular approach to Catholic moral teaching is that God has arbitary “rules” that he lays out because, hey!, he’s inscrutable and just like rules. “Morality” in such a system consists of “keeping the rules” because, well, rules are for keeping. If you break a rule, God will be veddy veddy angry because he just kind of a cosmic martinet who is that way. If you question the rules, you will get in Big Trouble because Rules are Rules.
In *actual* Catholic teaching, the “rules” are ordered toward protecting the dignity and integrity of the sort of creatures we are, living in relationship with one another and in the love of the sort of God God is. The rules are given so that we understand how to love in a way that is proper to our dignity as rational animals made in the image and likeness of God and (ultimately) as beloved children who have been made participants in the divine nature and even friends of God. This is why the tradition is so paradoxical about rules. On the one hand, they are recommended to us as tutors are given to lawless and woolly children who need some civilizing. But on the other hand, the rules are not God and cannot replace him. They are ordered toward grace and where grace operates, the rules can be transcended (though never broken). This is why Moses can command us to honor the Sabbath on pain of death and Jesus can say “The Sabbath was made for man, not man for the Sabbath.”